There is only one human soul, and it is infinite and eternal.
How do you know this?
You seem very confident in this assertion; I presume that you have lots of very strong evidence, and I would be grateful if you would share at least some of the most compelling parts of it.
A soul is an idea of God, and it abides eternally and infinitely in the mind of God.
A God is an idea of man, and it abides solely and ephemerally in the brain of man.
The soul of man is expressed materially in the infinite number of individual men.
The number of individual men will never exceed about 10-12 billion simultaneously, and is highly unlikely to exceed 10
15 in total, ever - Humans have only existed for a few tens of thousands of years, and are likely to be extinct within a million generations.
Each individual man embodies the soul of man in a specific way. The essence of man’s soul is reason.
Then where does God come into it? Gods are fiction, and fiction is by definition not subject to reason.
Reality does not contradict itself; It is internally consistent. Fiction can contradict itself in literally any way we can imagine.
The more an individual man identifies himself with reason, the more he shares in the eternal and infinite soul of mankind, and the less he concerns himself with his own individual death.
FTFY. There is no reason to concern ourselves with the inevitable; Souls (like everything else) are irrelevant to that simple fact.
Immortality of any kind is impossible, and to strive for it, plan for it, or anyicipate it is therefore futile.
The impossible is the easiest task of all, because we can always achieve the optimum result, with zero effort.
If Max Tegmark is correct in claiming the universe/God is an expression of all the possibilities in mathematics, and human consciousness is a mathematical entity, I suppose that makes some degree of sense.
If we redefine "God" in that way, it becomes obvious that it is a redundant concept. Remove "/God" and your meaning is completely unchanged.
And still contains a very big, and unsupported, "if". Is Tegmark correct? What evidence do we have for that? It seems to me to be pure speculation, and as valuable an insight as "If we had some eggs, we could have bacon and eggs, if only we had some bacon".